Semi-autonomous sensory-motor control for upper limb prostheses

In the past decades, efforts have been made to establish man-machine interfaces
between prostheses and the human nervous system [1]. These interfaces have provided
some level of control and, in rare cases, the possibility to transmit some sensation to the
users. Nonetheless, clinical translation of advanced bidirectional sensory-motor control
interfaces has been limited.
An ideal prosthetic device should mimic the sensing and actuation capabilities of the
biological counterpart. Considering the sophisticated structure and neural control of
human limbs, this is an extreme challenge. While the mechatronic technology has been
developing rapidly in recent years, allowing us to come close to this ideal, the information
transfer between the prosthesis and the user offered by state-of-the-art man-machine
interfaces is still extremely low. Even advancing the interfacing technology, it is very
unlikely that neural interfaces can replicate all aspects of natural sensory-motor control.
While the prosthesis cannot be fully neurally "re-connected" to the user to exploit their
decision-making and sensory/control abilities, it is possible to enhance the device with its
own intelligence. This approach is a radically different conceptualization of an assistive
system with respect to current state-of-the-art, promoting the robotic controller from a
simple decoder of the user intent into an intelligent agent collaborating with the user in
accomplishing functional tasks. Within this approach, the user transmits information only
about a high-level goal (e.g., grasping a cup) while the details of the movements (e.g.,
specific approach trajectory, grasp type and size) unfold mostly subconsciously, mimicking thereby how healthy subjects control their limbs. The sensory-motor control would
therefore become semi-autonomous, as for most natural tasks that are executed without
consciously controlling all the body degrees of freedom and integrating sensory feedback.
The semi-autonomous approach to prosthesis control has been preliminary explored
mainly in relation to the motor part of the sensory-motor loop (e.g., from our research
group see the recent paper [2]) while semi-autonomous full sensory-motor loops have
never been explored in prosthetic systems.
In this project we propose the development of a semi-autonomous control system for
prostheses that integrate motor commands with sensory information in closed-loop
systems both at the user level (conscious sensory-motor control) and at an AI agent level
(autonomous sensory-motor control). These two sensory-motor loops share the task of
the ultimate activation of the prosthesis.

The CDT students will help create solutions for amputees and people with debilitating conditions such as stroke and diabetes, reducing mortality and enabling them to live more satisfying, productive and fulfilling lives. These solutions, co-created with industry and people living with disabilities, will have direct economic and societal benefits. The principal beneficiaries are industry, P&O service delivery, people who need P&O devices, and society in general.
Industry
The novel methods, devices and processes co-created with users and industry will have a direct economic value to our industry partners (by the creation of IP, new products, and improved industry and academic links). Our CDT graduates will be the natural potential employees of our industry partners and for companies in the wider healthcare technology sector. This will help address the identified critical skills need and shortage leading to improvement in the UK's competitiveness in this rapidly developing and growing global market. The CDT outcomes will help UK businesses spread risk (because new developments are well founded) and more confidently enter new markets with highly skilled employees (CDT graduates).

P&O service delivery
Doctoral engineering graduates with clinical knowledge are needed to improve the deployment of advanced technologies in practice. Our main UK industry partner, Blatchford, stated: "As technology develops it will become easier for the end-user (the patient), but the providers (the clinicians) are going to need to have a higher level of engineering training, ideally to PhD level". The British Association of Prosthetists and Orthotists estimates that no more than ten practising P&O clinicians have a PhD in the UK. Long-term P&O clinical academic leadership will be substantially improved by the CDT supporting a select number of clinically qualified P&O professionals to gain doctorates.

Users
The innovation of devices, use of device and patient monitoring, and innovation approaches in LMIC should not only lead to improved care but also lower healthcare costs. Diabetes UK estimates that the total healthcare expenditure related to foot ulceration and amputation in diabetes was £1billion (2014-15), with 2/3 of this related to foot ulceration. Small innovations could lead to large cost savings if targeted at the right aspects of care (e.g. earlier adoption, and reducing device abandonment).
An ability to work is fundamental to a person's place in society and their sense of purpose and has a significant societal impact in all territories. This is perhaps greatest in LMIC where attitudes towards disability may still be maturing, and appropriate social care infrastructure is not always in place. In these cases, an ability to work is essential for survival.
Improved design approaches will impact on all users regardless of context, since the device solutions will better match local and individual user needs. Addressing issues related to prosthetic/orthotic device abandonment (e.g. cosmesis) and improved adherence should also lead to greater social participation. Improved device solutions will shift focus from what users "cannot do" to what they now "can do", and help progress attitudes towards acceptance of disability.
Societal
The majority of the global P&O users are of working age, and a key economic impact will be keeping users in work. The average age at amputation due to diabetes is just 52 in the USA but much younger in countries with less well-developed health care and trauma services (e.g. 38 in Iran). Diabetes UK reports that 35-50% of people are of working age at diagnosis and that there are around 70,000 foot ulcers in the UK, precursors to amputation. There is a similar concern for stroke survivors around a quarter of whom are of working age and are 2-3 times more likely to be out of work after eight years.